Not Applicable.
Not Applicable.
Not Applicable.
This invention is related to car parking areas sometimes referred to as car parks, parking lots or parking garages. Specifically in the area of car parking management the invention is aimed at providing information to motorists as to where there are vacant car spaces and which sections or aisles are full. This is usually by way of active signs which would indicate xe2x80x98vacantxe2x80x99 or xe2x80x98fullxe2x80x99 while using arrows to denote the section or aisle being referred to.
The basic concept of using active signs in car parks whether in networks or otherwise to point out to motorists full or vacant areas is well established in various patent applications world wide. This general concept is not within the scope of this invention, though this invention through its application is meant to ultimately fulfill this goal.
Car park management systems of this sort can be generally grouped into two categories; firstly counting systems; and secondly systems using individual car space sensors linked to a central control.
This first type is the most simple and inexpensive though very limited in its application. It necessitates only one entrance and separate exit points to be monitored by sensors per counter. This means that it cannot be used to monitor a specific parking aisle which typically allows far too many separate entrance and exit points. It uses simple arithmetic to determine the occupancy state of the particular area and is subject to cumulative error from false detection of the sensors (e.g. from people or shopping trolleys etc.).
The second type tends to be more complex and expensive, the degree of which is directly proportion to the number of car spaces being monitored, but because it uses sensors in each car space its more flexible and it can be used to monitor any desired area of car spaces and any number of car spaces. This type of system is also significantly less affected by false detection as the information is not cumulative, typically resetting within a short time.
This invention uses the second concept while most particularly attempting to significantly reduce the cost and complexity involved in implementing it in areas from small to very large numbers of car spaces. Prior art concerning this type of system invariably involves using sensors capable of detecting vehicles within the car spaces in conjunction with a digital signaling system using a central processing point which polls each of these sensors periodically to ascertain the state of each space and hence the state of the area being monitored. See U.S. Pat. No. 5,432,508. In practice this involves having a sensor, microprocessor and supporting electronic circuitry within each car space. This arrangement also requires power as well as signaling buses running out into the car park.
The most cost effective type of sensor is a light sensor, infrared or visible light, whereby the vehicle blocks the source of this light causing a change in the sensors internal resistance. Prior art descriptions of this type of sensor are limited to using a discreet wavelength emitter mounted next to a light sensor sensitive to this wavelength in a unit mounted to the ceiling above the car space. A reflector is mounted on the floor of the car space. Again refer to U.S. Pat. No. 5,432,508. This is a well known and widely used arrangement in many fields. It is however probably too complex and expensive to put one of each of these components in every car space of which there may be 1000 or more. Also there is the unpredictable effects that sunlight, direct or reflected, has on this type of sensor. This is a well known problem concerning remote infrared signaling, therefore limiting this type of sensor to fully undercover areas. This in practice is particularly limiting as even most under cover car parks have open walls allowing sunlight to augment the artificial lighting.
This invention facilitates use in environments exposed to full sunlight, part sunlight/part artificial light and all artificial light. It does not need polling technology, microprocessors or computers. It uses in general one single visible light sensor component for each car space, connected together in very simple fashion. Every group of two to say ten car spaces may require an ambient light sensor that compensates for changing ambient conditions. Again the ambient light sensors are very simple (a light sensor and one transistor) connected in very simple fashion. In practice it uses three conductors and is laid into a shallow cut in the surface of the concrete in quick and simple fashion.
This invention was developed especially to allow ease of installation as well as accurate detection of the state of the car park. The first commercial and fully functioning system was installed in Southport, Australia in a shopping centre car park in March, 2001. It uses only those components defined in this specification.
The object of the invention is to facilitate car park occupancy active signage systems (car park management systems) in a cost effective and relatively simple fashion. These types of systems by way of changeable or active signs indicate to motorists within car parking areas which sections or aisles have vacant parking spaces and which are fully occupied.
The invention facilitates this objective by placing one or two sensors in the middle of each of the relevant monitored car spaces which indicates whether a vehicle occupies the car space or not. These sensors are discreet light sensitive transistors or diodes which in practice detect the shadows of vehicles.
Other proposed systems require much more complex hardware and higher cost sensor arrangements which must be duplicated for each and every car space monitored.
With simple and inexpensive circuitry this invention is able to indicate whether a group of car spaces has one or more vacant spaces or is completely full. It performs this function without digital address buses, digital multiplexing, microprocessors, computers or periodic polling of the individual sensors.